Odontoid fractures are becoming more prevalent as the population ages. Both nonoperative and external fixation of geriatric odontoid fractures are associated with a high rate of non-union or poor outcome. Furthermore, recent data from an AOSpine North America study group support operative intervention in the elderly.
There are numerous options for internal fixation of odontoid fractures. These options include posteriorly based approaches and anteriorly based approaches. Posterior approaches include C1-C2 transarticular screws, posterior sublaminar wiring, and the use of C1 lateral mass screws with either a C2 pedicle, pars, or translaminar screws. Unfortunately, there are disadvantages of posterior fixation in the elderly, including the loss of joint motion and poor wound healing.
Anterior approaches include fixation using odontoid screws in which a single lag screw is inserted across the fracture line at the base of the dens using a standard Smith-Robinson approach. Such a procedure provides several advantages over posterior approaches. For example, this anterior approach is minimally invasive, motion preserving, and tends to have better wound-healing profiles than posterior approaches. However, fixation using a single odontoid screw is not suitable for every case, especially with patients with anterior oblique fractures, those having injury to the transverse and alar ligaments, or those with an unfavorable body habitus.
Another anterior approach that has been described in the literature is a transoral approach in which access to the vertebrae is achieved by making an incision in the posterior of the pharynx. In this approach, anterior C1-C2 transarticular screws are inserted either with or without a Harm's plate. Biomechanical testing has demonstrated that the procedures using a Harm's plate were inferior to all of the above-mentioned techniques. Although standalone anterior C1-C2 transarticular screws were observed to be noninferior to posterior C1-C2 transarticular screws, the transoral approach is unattractive as there are risks of contamination from exposure to bacteria within the mouth and pharynx.
In view of the above discussion, it can be appreciated that it would be desirable to have apparatuses and methods for achieving effective anterior cervical transarticular fixation that do not require a transoral approach.